It's time to start the Pickling experiment. Choose the experimental parameters: remember that temperature is important.
You can ask the colleagues in the lab to analyse the ferrous solution to decide if the process has been effective. To do so, you can take an aliquot of the ferrous solution (1 mL) and measure the Fe concentration in the solution by means of Inductively Coupled Plasma Mass Spectrometry (ICP-MS). If the Fe concentration is around 100 g/L, you succeeded in dissolving the contaminated layer!
You can check if the pickling process succeeded by measuring the residual contamination on the pipe sample. Ask the colleagues of the radiometric lab to perform a radiometric measurement on the pipes. Then you will be able to decide if the metal pipes can be released by comparing the residual activity with the clearence levels.
For the next steps you will need to know the total activity of the ferrous solution, send an aliquot of ferrous solution (10 mL) to the colleagues of the radiometric lab to perform a radiometric measurement on the solution. Set aside it for the next step. You will receive from the lab the radiometric data (net counts of the radionuclide in the region of interest (ROI), counting efficiency and counting time) and you can calculate the total activity of each radionuclide by the following formula:
\[ \text{A[Bq/mL]} = \frac{\text{net count}}{\text{eff} \cdot t \cdot V} \]
Pay attention, you are working with radioactive materials!